Review

TARE (Y-90 / Ho-166) dosimetry

Activity planning for radioembolisation: partition model, single compartment (MIRD), lung dose and product-specific limits; comparison with the historical BSA method for resin. Calculated in your browser and never stored.

Under review: thresholds are taken verbatim from EANM 2022 Tables 2–4 and Levillain 2021; use for education only until reviewed by a physician and a medical physicist.

Patient and planning values

Volumes from CT/MRI or cone-beam CT; T/N and shunt fraction from Tc-99m MAA SPECT/CT (shunt also from planar imaging). Mass = volume × 1.03 g/mL (AAPM MPPG 14.a).

Activity and doses

Activity
1.64 GBq (44.3 mCi)
Tumour (mean)
205 Gy within limit
Perfused non-tumoural liver
51 Gy
Whole non-tumoural liver
51 Gy within limit
Perfused volume (single compartment)
74 Gy
Lung
4.9 Gy within limit
Fraction of activity in tumour
41%
Maximum activity by lung limit
10.07 GBq (272.1 mCi)
Maximum activity by normal liver limit
2.40 GBq (64.8 mCi)
  • Tumour ≥ 205 Gy (≥ 250–300 Gy better response) [EANM 2022 Tablo 2]
  • Whole non-tumoural liver < 75 Gy (generally < 75; 50 if bilirubin > 1.1 mg/dL, up to 90 if < 1.1) [EANM 2022 Tablo 2]
  • Single-compartment approach: perfused volume 80–150 Gy [EANM 2022 Tablo 2]
  • Values derive from glass microspheres used in week 1 after calibration; no dosimetric data for week 2.
  • Lung: ≤ 30 Gy per session, ≤ 50 Gy cumulative (planar MAA, 1 kg lung) [EANM 2022; Levillain R26].

D (Gy) = 49.67 × A (GBq) × fraction / m (kg) · 15.87 for Ho-166 · tumour fraction = T/N·m_T / (T/N·m_T + m_N) · lung = 49.67 × A × shunt / m_lung

Where the activity goes and compartment dosesPhysician review done; awaiting medical physicist review

Anterior torso drawing: microspheres given through the catheter into the hepatic artery. Part stays in the vial, the lung shunt fraction passes through intratumoural shunts via the hepatic veins, IVC and right heart to the lungs, and the rest is split between tumour and perfused normal liver by T/N ratio and mass; the last step shows each compartment's dose from the entered values.

LungsHeartSpleenLiverIVCAorta · catheterHepatic arteryPortal veinVialTumour205 Gy51 Gy4.9 GyTumour: sphere equal to 150 mL, true scale; perfused territory schematic1 dot ≈ 0.02 GBq (0.6 mCi) (dot count representative)0205 GyAbsorbed dose

4 Dose = activity × 49.67 J/GBq ÷ mass. Tumour 205 Gy, normal liver 51 Gy, lung 4.9 Gy.

Where the activity goes

1.64 GBq (44.3 mCi) from the vial

  • Left in vial / catheter0.00 GBq (0.0 mCi) · 0.0%
  • Lung (shunt)0.10 GBq (2.7 mCi) · 6.0%
  • Tumour0.64 GBq (17.2 mCi) · 39%
  • Perfused normal liver0.90 GBq (24.4 mCi) · 55%

One microsphere (true scale)

25 µmred cell 7.5 µm10 µmGlass: Y-90 within the glass matrix

Mean diameter 25 µm (20–30), density 3.3 g/mL, ≈ 2500 Bq per sphere (calibration day). ≈ 0.66 million spheres for the delivered activity (more in practice, as activity per sphere falls by treatment day). Imaging: Y-90 PET, bremsstrahlung SPECT.

Source: d'Abadie et al., Molecules 2021;26:3966 (Table 2); Ho-166 size range NICE TA688 protocol (2019).

Dose = activity × 49.67 J/GBq ÷ mass

Tumour205 Gy
0.64 GBq (17.2 mCi) × 49.67 ÷ 0.15 kg
≥ 205 Gy · within
Perfused normal liver51 Gy
0.90 GBq (24.4 mCi) × 49.67 ÷ 0.88 kg
Whole non-tumoural liver51 Gy
0.90 GBq (24.4 mCi) × 49.67 ÷ 0.88 kg
≤ 75 Gy · within
Perfused volume (single compartment)74 Gy
1.54 GBq (41.6 mCi) × 49.67 ÷ 1.03 kg
≥ 80–150 Gy · below target
Lung4.9 Gy
0.10 GBq (2.7 mCi) × 49.67 ÷ 1.00 kg
≤ 30 Gy · within

Activity window

Between the least activity needed for the scenario's targets and the most the safety limits allow (green).

  • Least for the Tumour target: 1.64 GBq (44.3 mCi)
  • Least for the Perfused volume (single compartment) target: 1.76 GBq (47.7 mCi)
  • Most for the Whole non-tumoural liver limit: 2.40 GBq (64.8 mCi)
  • Most for the Lung limit: 10.07 GBq (272.1 mCi)
  • Chosen activity: 1.64 GBq (44.3 mCi)
Liver map: segments, arteries, lesionsPhysician review done; awaiting medical physicist review

Anterior view of the liver with Couinaud segments; a labelled hepatic arterial tree from the coeliac trunk to the segmental branches, the chosen catheter tip and the segments it supplies; each lesion in its own segment at true size with its own dose; gastroduodenal, right gastric and cystic arteries and coils.

IIIIIIVaIVbVVIVIIVIII205 GyCoeliac trunkCommon hepatic a.Proper hepatic a.Right hepatic a.Right anterior branch (V, VIII)Right posterior branch (VI, VII)Left hepatic a. (II, III)Middle hepatic a. (IV)Gastroduodenal a.Right gastric a.Cystic a.StomachDuodenumGallbladderLesions are spheres of equal volume at true scale; segment borders schematic; spheres representative

3 Activity reaching the liver is shared between perfused lesions and non-tumoural liver by (T/N) × mass; each lesion's dose is its T/N times the non-tumoural liver dose.

Hepaticoenteric branches and coils

Lesions

L1

You choose each lesion's segment (no automatic Couinaud segmentation from CT). Volume and T/N can be transferred from image analysis.

Dose (multi-compartment partition model)

L1 · VIII · 150 mL · T/N 4205 Gy
≥ 205 Gy · within
Perfused non-tumoural liver51 Gy
D = 49.67 × 1.54 GBq ÷ 1.494 kg; Di = (T/N)i × D
Lung4.9 Gy

Hepaticoenteric branches and coils

Risk of non-target deposition — Cystic a.: very close to the catheter tip (reflux)

Routine protective coiling is no longer recommended; if a branch arises beyond or right next to the catheter tip, it is coiled or the catheter is advanced past it (Borggreve et al. 2016; Semin Intervent Radiol 2021).

Perfused non-tumoural volume comes from the input above; when the catheter tip changes, the perfused territory on MAA changes too, so update that volume above. Lung dose is for the whole injection.

Red dots going to the stomach, duodenum or gallbladder are representative (fraction not measured) and are not counted in the dose. Variant frequencies Michels 1966: classic ~55%, left hepatic from left gastric ~10%, right hepatic from SMA ~11%.

Post-treatment verification

Enter the mean absorbed doses measured on post-treatment Y-90 PET/CT (or bremsstrahlung SPECT/CT) dosimetry; deviation from the plan and compliance with thresholds are shown. EANM: confirm sufficient tumour uptake, acceptable lung dose and no visceral deposition.

Measured values are not stored on this page. Voxel dosimetry and DVH from images will come with the image analysis module (PLAN 3.26).

Sources: Weber M ve ark. EANM 2022 (doi:10.1007/s00259-021-05600-z); Levillain H ve ark. 2021 (doi:10.1007/s00259-020-05163-5); Busse NC ve ark. AAPM MPPG 14.a 2023 (doi:10.1002/acm2.14157).

Assumptions: microspheres are distributed homogeneously in each compartment, energy is absorbed locally, no biological clearance; non-perfused liver receives no dose; bremsstrahlung is neglected. Doses from sequential treatments are not simply summed (EANM 2022).

For education and research; not clinical decision support. Real planning follows the institution's protocol, the product's instructions for use and a medical physicist.